When I built my new iMac last month I disabled Time Machine via its preference panel.
Last week I had problems with Entourage04 suddenly crashing every so often -- and after a bit of troubleshooting, I noticed that TM was turned ON. Once I turned TM off, Entourage worked fine again.
Based on my own experience and what I have heard from 2 other users across the country, I suspect that the last Apple SW update re-enabled TM, but I can't confirm it.
Anyone else notice that?